Apparatus and method for detection and measurement of environmental parameters

ABSTRACT

The present invention provides a device for in-situ measurement and recording of various environmental parameters in a semiconductor fabrication process. The device comprises sensors for detecting the parameters and converting them to sensor outputs; and a data logger coupled to the sensors for receiving the sensor outputs and logging them in a file. The device may also comprise an analog to digital converter to convert the sensor outputs to digital data and a communication module to communicate the digital data with other devices. When applied to reticles used in a semiconductor fabrication process comprising a plurality of stages, the device may be used to monitor electrostatic field and electrostatic discharge activities on and around the reticle, convert the monitored parameters into data, and log the data along with a timestamp and an identification of each individual stage. Logged data can be retrieved and analyzed to determine the time and location of detrimental activities such as electrostatic discharge on reticles.

FIELD OF THE INVENTION

[0001] This invention relates generally to a system and method formonitoring process and environmental parameters in a manufacturing orother process and in particular to a monitoring system for a processwhere it is not possible to use conventional monitoring methods due tomovements of the monitored object.

BACKGROUND OF THE INVENTION

[0002] It is desirable to be able to monitor various process andenvironmental parameters associated with a process to determine how wellthe process is functioning. For example, the temperature of a CVD(chemical vapor deposition) process (a critical parameter associatedwith the CVD process) may indicate the quality of the film beingdeposited by the CVD process at the time in question. For a non-movingobject, there are many conventional process monitoring systems whichpermit various parameters to be determined. Unfortunately, it isdifficult for such a conventional system to be used with a object thatis moving during the process in question. To better understand theproblem, an example of a particular moving object (e.g., a reticle in asemiconductor manufacturing process) that needs to be monitored will bedescribed, but it should be understood that the problem is associatedwith any moving object that needs to be monitored.

[0003] A reticle in a semiconductor manufacturing process is a speciallymade photo “negative” used to expose a photosensitized semiconductorwafer prior to etching in order to ultimately produce a plurality ofintegrated circuits (IC) on the semiconductor wafer. A typical reticleis made of quartz with thin chrome traces on it representing the desiredelectrical connections for the particular IC. Modern recticlcs withsmall geometry (e.g., very fine lines and a small spacing between thelines corresponding to the very close electrical traces on moderns ICs)are particularly sensitive to various environmental and processparameters, such as exposure to electrostatic voltages. As a result ofthis exposure, the thin traces on the reticle can be damaged ordestroyed and the process engineer may not realize that the reticle hasbeen damaged.

[0004] Even a small number of damaged reticles can causedisproportionately large losses because the damaged reticles can goundetected and be used in a photolithography process to produce a largenumber of defective ICs, which are expensive to manufacture. Further, inaddition to replacement costs of defective ICs and reticles, the downtime of a fabrication facility may significantly add to the losses.Thus, it is necessary to detect and replace defective or damagedreticles from the semiconductor fabrication process as early aspossible. Unfortunately, the sources of electrostatic damage forreticles are varied and unpredictable because reticles go through anumber of different handling stages for use in a semiconductorfabrication process. For example, reticles stored in a storage placemust be retrieved and loaded into a loader. Then the reticles are loadedfrom the loader to a stepper that is used in a photolithography process.After use, reticles are unloaded from the stepper back into the loaderand carried back to the storage place. Reticles also go through severaltesting stages where they are subjected to various physical tests.

[0005] If a reticle comes into close proximity with an electric chargebearing object during any of the handling or testing stages, it maysustain electrostatic discharge damages. For example, the test pads onwhich the reticles are placed may be a source of electric discharge.Even if the reticle does not sustain an immediate electrostaticdischarge damage, the effect may accumulate in the reticle, so that thereticle becomes more and more vulnerable to electrostatic discharges.

[0006] Thus, it is desirable to provide monitoring capability forreticles' exposure to electrostatic damages so that the process engineerwould be able to identify and inspect exposed reticles in order todetect damaged reticles prior to beginning the fabrication. Themonitoring would also permit the process engineer to identify specificoccurences of exposure in order to try to reduce those exposures in thefuture. The problem with using typical monitoring system is that thereticles travel throughout the semiconductor fabrication facility and itis impossible to monitor them at all times with stationary monitors.

[0007] Some attempts have been made to provide portable data storagesystems that can travel along with the reticle in the reticle storagepod, such as Smart-Tag system by Asyst. This system consists of aminiature data storage device and an RF-ID module that can communicatewith a corresponding stationary device that reads and writes data intothe tag that moves with the reticle. This system, however, does notobserver or record any in-process parameters.

[0008] Other conventional devices provide rudimentary means forrecording parameters such as exposure to electrostatic charges. Anexample of it is the “Ex-Mod” device by Ex-mod Corporation and StaticBug by ElectroStatic Designs. These devices must be installed on thehost (i.e. on a circuit board or a wafer) that goes through the process.They provide indications that a parameter (e.g., electrostatic exposure)has exceeded a certain level somewhere along the process. However, theydo not provide information to correlate collected data points to aspecific step in the process or a time frame during the process. Thus,data provided by conventional monitoring devices are difficult tointerpret and analyze. Also the conventional monitoring devices aredifficult to reset, and they must be completely replaced for re-use.

[0009] Thus, it is desirable to provide an in-situ monitoring of variousparameters, such as electrostatic discharges and damages, that overcomesthe above limitations and problems with conventional monitoring systems.It is also desirable to provide a data logger system so that parametersmonitored in situ may be logged and communicated for further processing.It is to these ends that the present invention is directed.

SUMMARY OF THE INVENTION

[0010] The present invention provides a device for in-situ measurementand recording of various environmental parameters in a manufacturingprocess such as a semiconductor fabrication process The device comprisessensors for detecting the parameters and converting them to sensoroutputs; and a data logger coupled to the sensors for receiving thesensor outputs and logging them in a file. The device may also comprisean analog to digital converter to convert the sensor outputs to digitaldata and a communication module to communicate the digital data withother devices or to a centralized base station.

[0011] The communication module may comprise an RF (radio frequency)transmitter and a receiver to allow operators to interact with thedevice for downloading of the collected data and control of the device.The sensors on the device may include an electrostatic field sensor todetect and measure a presence or change in electrostatic field, and anelectrostatic discharge sensor to detect and measure an electrostaticdischarge. The data logger permits the device to continuously monitorand collect the necessary sensor data as well as timestamp them. Thetimestamped sensor data can be downloaded at a convenient time forsubsequent analysis. Alternatively, the collected data may be presentedon a built-in visual display for immediate inspection.

[0012] When applied to reticles used in a semiconductor fabricationprocess comprising a plurality of stages, the device may be used tomonitor electrostatic field and electrostatic discharge (ESD) activitiesaround the reticle, convert the monitored parameters into data, and logthe data along with an identification of each individual stage. Loggeddata can be retrieved and analyzed to determine the time and location ofdetrimental activities such as electrostatic discharge on reticles. Whenthere is a combined occurrence of electrostatic discharge andelectrostatic field from the monitored readings, it is likely toindicate a valid local ESD event. Extraneous electrostatic dischargesmay be filtered and excluded using various criteria based on the sensoroutputs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 illustrates an example of a device in accordance with theinvention that is attached to a product in process of being manufacturedor otherwise processed;

[0014]FIG. 2 illustrates a block diagram of one embodiment of the datalogging system in accordance with the invention;

[0015]FIG. 3 illustrates a data logging unit 36 in accordance and baseequipment 44 in accordance with one embodiment of the invention;

[0016]FIG. 4 illustrates an example of a device 50 with an electrostaticsensor and a signal processing circuit for detecting and measuringchanging electrostatic field in accordance with one embodiment of theinvention;

[0017]FIG. 5 illustrates a detailed schematic diagram of anelectrostatic sensor and a signal processing circuit for detecting andmeasuring changing electrostatic field using the device of FIG. 4 inaccordance with one embodiment of the invention;

[0018]FIG. 6 illustrates an example of a device 100 with a doubleelectrode sensor and a signal processing circuit for detecting andmeasuring changing electrostatic field in accordance with one embodimentof the invention;

[0019]FIG. 7 illustrates a detailed schematic diagram of the sensorelements 104 and 106 and the signal processing circuit 102 of FIG. 6 inaccordance with one embodiment of the invention;

[0020]FIG. 8 illustrates an example of a single electrode sensor and asignal processing circuit for detecting and measuring changingelectrostatic field in accordance with one embodiment of the invention;

[0021]FIG. 9 is a diagram illustrating an electrostatic discharge (ESD)monitoring sensor that may be used to monitor ESD events; and

[0022]FIG. 10 illustrates a circuit diagram of an ESD event monitorconstructed in accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0023] The invention is particularly applicable to the monitoring ofprocesses and environmental parameters wherein the monitored object ismobile and it is in this context that the invention will be described.While the invention will be described in conjunction with the preferredembodiments, it is understood that the description is not intended tolimit the invention to these embodiments. Rather the invention isintended to cover alternatives, modifications and equivalents, which maybe included within the scope of the invention. For ease of explanation,the following description will focus specifically on processes andenvironmental parameters associated with reticles used in asemiconductor fabrication process. The processes monitored include, butare not limited to, retrieval of reticles from storage area, loading ofreticles into steppers, and scanning of the reticles in aphotolithographic process. The parameters monitored include, but are notlimited to, a reticle serial number, process tracking information,presence of electrostatic fields, magnitude of electrostatic fields,polarity of electrostatic discharges and magnitude of electrostaticdischarges. However, it will be appreciated that the system and methodin accordance with the invention have greater utility, and may beextended beyond the semiconductor fabrication process to any otherprocess which require monitoring of environmental parameters.

[0024]FIG. 1 illustrates an example of a device in accordance with theinvention that is attached to a product in the process of beingmanufactured or otherwise processed. In particular, a reticle 10 with apellicle (a protective clear film) 12 is used in photolithographyprocess as described above and as is well known. A logging device 14 inaccordance with the invention is attached to the reticle 10 in a fashionthat does not impede the processing of the reticle. Similarly, thelogging device 14 may be attached to any object in a non-invasivefashion wherein the object is moving through a manufacturing process.Now, an embodiment of the data logging system will be described.

[0025]FIG. 2 illustrates a block diagram of one embodiment of the datalogging system in accordance with the invention. In particular, a datalogger 20 (that may be an ASIC, a piece of hardware circuitry or one ormore pieces of software being executed by a processor) collects datafrom one or more well known sensors 22 (Sensor 1, Sensor 2, . . . Sensorn). Each sensor provides data about one or more parameters important tothe user. For reticle handling, for example, it is important to knowsuch parameters as 1) the presence and strength of an ESD events; and 2)the rate of change and magnitude of the electrostatic fields. Otherparameters can be measured as well since various different types ofsensors can be connected to the data logger 20. The signal from eachsensor may be conditioned and processed by a signal processing circuit23 if needed. The processed signal then is provided to said data logger20 which may contain one or more analog-to-digital converters 24 thatconverts the analog sensor signals into digital data as is well known inthe art. Analog to digital conversion is used to enable storage andcommunication of data in digital format instead of analog format. It isalso possible that a sensor may generate a digital signal and an A/Dconverter 24 may not be required. The data logger 20 may operate withsensors that generate analog signals as well as sensors that generatedigital signals.

[0026] The data logger 20 records the collected data into a memory 26that may be attached to the data logger as shown in FIG. 2 orincorporated into the data logger. The memory 26 may be implemented by aflash memory, a RAM (random access memory), or other storage devices.Preferably, the data logger 20 comprises a timestamping module in orderto time stamp the information logged into the memory 26. Any well-knowntechnique may be used to implement the timestamping module. For example,the data logger 20 may have an internal clock circuitry such as based ona crystal oscillator to keep track of time. Alternatively, thetimestamping module may use an external clock circuitry to keep track oftime. Preferably, the timestamping module comprises software residing inan internal or external memory to monitor the clock and record time inthe memory 26 along with the collected data.

[0027] Unlike conventional ESD detectors, the invention allowscontinuous monitoring of environmental parameters. In typical ESDdetectors, once an ESD event occurs, it blows the circuitry, terminatingany subsequent EDS event monitoring. In contrast, the invention allowscontinuous monitoring and data logging by providing a data logger sothat sensor data can be collected and saved in a memory. The sensor datasaved in the memory can be retrieved at any convenient time for furtherprocessing and analysis.

[0028] The communication between the data logger 20 and other equipmentis done with the help of a communication module 28. A power signal isprovided to the data logger 20 by a battery 30 (disposable orrechargeable) or via other power sources. In an alternate embodiment ofthe invention, data from data logger 20 may be displayed on a built-indisplay 32, such as a liquid crystal display (LCD) or the like. In yetanother embodiment of the invention, optional control components 34(i.e. switches, etc.) can be used to locally control the data logger 20.

[0029] The data logging unit can be made using discrete components orusing an integrated component containing all or some of its parts in oneintegrated solution, such as IC or MCM (multi-chip module) as should beobvious to one skilled in art.

[0030]FIG. 3 illustrates a data logging unit 36 in accordance and baseequipment 44 in accordance with one embodiment of the invention. In apreferred embodiment of the invention, the base equipment 44 comprises abase RF transmit/receive circuit 45 and an antenna 46. In a preferredembodiment, the data logging unit 36 embodies a battery 42, sensors 37,a signal processing circuit 38, a data logger 39, an RF transmit/receivecircuit 40, and an antenna 41 in a linear arrangement so that the wholeunit 36 can be enclosed in a small unobtrusive package and fit on theside of the reticle 10 as illustrated in FIG. 1. However, it will beapparent to one skilled in the art that other configurations orarrangements of the components inside the unit 36 are possible.

[0031] In operation, sensors 33 convert parameters of interest intoelectric signals, which are conditioned by a signal processing circuit38. In an alternate embodiment of the invention, the signal processingcircuit 38 is not required for the data logging unit 36. Processedsignals are recorded or otherwise processed by the data logger 39.

[0032] Exchange of information between the data logger 39 and externalequipment may be done by the RF transmit/receive circuit 40 and theantenna 41. The types of information communicated by the data loggingunit 36 include data, control signals for the data logger 39, reticleidentification information, and process tracking information. It will beapparent to one skilled in the art that other types of information mayalso be communicated. Data exchange may be continued with other devicesor a centralized base station using conventional communication means 47.For example, an RF ID (radio frequency identification) technique can beused as the communication means 47.

[0033] The base equipment 44 may also have the capability to bothtransmit and receive data with the data logger unit 36 via the base RFtransmit/receive circuit 45 and the antenna 46 so that data parametersof interest that are recorded in the data logger 39 can be retrieved bythe base equipment for further processing. The base equipment 44 mayalso transmit control signals to the data logging unit 36 in order toset its parameters and give instructions.

[0034] In contrast to conventional ESD detectors, the sensor data can beautomatically collected by the base equipment 44 without the need for amanual inspection of the ESD sensor device by using the RFtransmit/receive circuit 40. Further, the transmission and reception ofthe sensor data can be handled by using conventional techniques withouthaving to change or reinstall communication equipment. Thus, theinvention enables an interrupt-free, seamless incorporation of the ESDmonitoring process into the semiconductor fabrication process.

[0035]FIG. 4 illustrates an example of a device 50 with a, electrostaticsensor and a signal processing circuit for detecting and measuringchanging electrostatic field in accordance with one embodiment of theinvention. The electrostatic field is monitored because a sufficientlystrong change in electrostatic field can be a cause of damage or harm toa reticle. In FIG. 4, an electrostatic sensor comprising two pairs ofsensor plates (A-1, A-2, B-1 and B-2) including 54, 56 and 58, 59respectively, is coupled to a signal processing circuit 60.

[0036] In operation, the sensors A and B of FIG. 4 receive differentelectric signals when an electrically charged object generating staticfield approaches the sensor plates from a horizontal direction. Theelectrical signals from the sensor plates A and B are then provided tothe signal processing circuit 60 for further processing. It will beapparent to one skilled in the art that by adding more sensor plates andmodifying the geometry of the sensor plates, it is possible to detectchanges in electrostatic field from all directions (360 degrees in allspatial planes).

[0037]FIG. 5 illustrates a detailed schematic diagram of anelectrostatic sensor and a signal processing circuit for detecting andmeasuring changing electrostatic field using the device of FIG. 4 inaccordance with one embodiment of the invention. In FIG. 5, the sensorelements 54 and 56 are coupled to an operational amplifier (op amp) 62via resistors 64 and 66, respectively. The op amp 62 is coupled to asignal processing circuit 52. The resistor 64 is coupled to ground via aresistor 68 and a bias supply circuit 72. The resistor 66 is alsocoupled to a resistor 70. The sensor elements 58 and 59 are coupled toan operational amplifier (op amp) 79 via resistors 80 and 82,respectively. The op amp 79 is coupled to the signal processing circuit52. The resistor 80 is coupled to ground via a resistor 88 and a biassupply circuit 90. The resistor 82 is also coupled to a resistor 86. Abattery 74 or other suitable power source is provided to power the opamp 62.

[0038] In operation, the op amp 62 and resistors 64, 66, 68 and 70amplify the difference in voltage generated by the sensor elements 54and 56, and provide the amplified signal to the signal processingcircuit 52. The bias supply circuit 72 is used to establish operatingparameters of the circuit as is well-known in the art. In one embodimentof the invention, the sensors 54 and 56 detect a magnitude of changingelectrostatic field and feeds the information to the signal processingcircuit 52. The op amp 79 and resistors 80, 82, 86, and 88 amplify thedifference in voltage generated by the sensor elements 58 and 59, andprovide the amplified signal to the signal processing circuit 52. Usingfour (4) sensor elements, 54, 56, 58 and 59, permits to determine thedirection of electrostatic field as well as its presence.

[0039]FIG. 6 illustrates an example of a device 100 with a doubleelectrode sensor and a signal processing circuit for detecting andmeasuring electrostatic field in accordance with one embodiment of theinvention. In FIG. 6, an electrostatic sensor comprising circularelectrodes 104 and 106 are coupled to a signal processing circuit 102.Compared to the circuit shown in FIG. 4, the circuit of FIG. 6 issimpler and smaller because of reduced number of circuit components.However, the circular sensor of FIG. 6 is not capable of determining thedirection of electrostatic field whereas the sensor of FIGS. 4 and 5 candetermine the direction of electrostatic field. FIG. 7 illustrates adetailed schematic diagram of double circular sensor elements 104 and106, and the signal processing circuit 102 of FIG. 6 in accordance withone embodiment of the invention. In FIG. 7, an electrostatic sensorcomprising the circular sensor elements 104 and 106 is coupled to an opamp 108 via resistors 114 and 116 respectively. The op amp 108 iscoupled to the signal processing circuit 102. The resistor 116 iscoupled to ground via a resistor 110 and a bias supply circuit 118. Theresistor 114 is also coupled to a resistor 112. A battery 120 or othersuitable power source is provided to power the op amp 108.

[0040] In operation, the op amp 108 and resistors 114 and 116 amplifythe difference in voltage generated by the sensor elements 104 and 106,and provide the amplified signal to the signal processing circuit 102.The bias supply circuit 118 is used to establish operating parameters ofthe circuit as is well-known in the art. The sensors 104 and 106 maydetect a magnitude of changing electrostatic field and feed theinformation to the signal processing circuit 102.

[0041]FIG. 8 illustrates an example of a single electrode sensor and asignal processing circuit for detecting and measuring changingelectrostatic field in accordance with one embodiment of the invention.In FIG. 8, a single electrode sensor 150 is coupled to a signalprocessing circuit 162. A single electrode sensor configuration can beconstructed from a multi-electrode sensor configurations. For example, asingle electrode sensor can be obtained from the double electrode sensorconfiguration such as shown in FIG. 6 by connecting one electrode to theground plane of the circuit. Although a circular-shaped single electrodeis shown in FIG. 8, other shapes may be used to implement the singleelectrode 150. For example, a square-shaped, triangle-shaped, orpentagon-shaped electrode may be used as the single electrode 150.

[0042] In operation, the sensing electrode 150 detects electric fieldand converts it into an electric signal. An op amp 152 and resistors154,156 and 158 provide amplification of the signal processing circuit162. A power source 160 is provided to power the op amp 152.

[0043]FIG. 9 is a diagram illustrating an electrostatic discharge (ESD)sensor that may be used to monitor ESD events. In FIG. 9, an ESD eventmonitor is coupled to an antenna 182. An ESD event monitor of anysuitable construction may be used as the ESD event monitor 160. Furtherdetails concerning ESD event monitors such as that shown in FIG. 9 maybe found in U.S. pat. application Ser. No. 09/551,412 entitled,“Electrostatic Discharge (ESD) Event Monitor,” filed Apr. 18, 2000 whichis incorporated herein by reference. The output of the ESD event monitor180 is provided to a data logger such as the data logger 39.

[0044]FIG. 10 illustrates a circuit diagram of an ESD event monitorconstructed in accordance with one embodiment of the invention. In FIG.10, an antenna 202 is coupled to a window comparator 200 (well-known inthe art, and thus not shown in detail) via a capacitor 204. Inoperation, the window comparator 200 provides a logic-level signalwhenever the input signal, or as in this particular case, the magnitudeof an ESD event of any polarity exceeds a pre-determined thresholdvalue. The antenna 202 detects a change in electromagnetic field causedby an ESD event and converts it into an electric signal. The capacitor204 provides DC (direct current) decoupling of the electric signalreceived from the antenna 202 if necessary. Resistors 206 and 208 formbias circuit for the input signal. Voltage dividers comprising resistors210, 212, 214 and 216 provide reference voltages for positive andnegative peaks of an input signal. The output of the window comparator200 is provided to a data logger such as the data logger 39 for furtherprocessing.

[0045] Often, there is a need to localize ESD events and filter andeliminate extraneous ESD events. For various reasons such as relativesignal strength, an extraneous ESD event may be mistaken for a local ESDevent. Extraneous ESD events refer to ESD events detected by the ESDsensor that do not cause electrostatic damages to the reticle becausethey occur at a location remote from the reticle such as on an apparatusor equipment. On the other hand, valid ESD events occur on the reticleitself or in a closer proximity thereto so that they can causeelectrostatic damages to the reticle or an object of interest. Thus, inorder to eliminate such extraneous ESD events, both electrostatic fieldand ESD may be monitored and localized in accordance with one embodimentof the invention. Table 1 shows an example of sensor data logged over aperiod of time by an electrostatic field sensor and an ESD sensor. TABLE1 Entry No. Time Electrostatic Field (V) ESD Events Detected 1  9:53:222000 0 2  9:55:44 3420 1 3 10:00:28 1890 1 4 10:09:56 5230 18 5 10:12:1820 2 6 10:14:40 3490 4 7 10:17:02 2800 0 8 10:19:24 800 0 9 10:21:46 1200 10 10:35:58 4200 12 11 15:05:22 2900 2

[0046] Referring to Table 1, information in Table 1 can be used tolocalize ESD events and eliminate extraneous ESD events. For example,information entry 10 is likely to indicate valid ESD events on thereticle because they were accompanied by a high level of electrostaticfield (4200 V). On the other hand, information logged in entry 5 islikely to indicate extraneous ESD events because even though there wereESD events detected, the level of electrostatic field detected wasrelatively low (20 V) so that the ESD events are not likely to haveoccurred on the reticle itself or in a sufficiently close proximitythereto.

[0047] It will be appreciated by one skilled in the art that variousmethods may be used to eliminate extraneous ESD events, and recognizevalid ESD events. For example, occurrences of ESD event andelectrostatic field may be separately recorded as illustrated inTable 1. Collected data then can be reviewed so that the ESD events thatoccur in the absence of electrostatic field are discarded as extraneousESD events. Alternatively, extraneous ESD events may be eliminated bylogging ESD events only when there is a certain level of electrostaticfield build-up combined with an ESD detection. In yet another embodimentof the invention, an ESD event may be recorded only if there is anabrupt change in electrostatic field accompanying the ESD event.

[0048] The process of localizing ESD events and eliminating extraneousevents may be implemented using hardware, software or in combinationthereof. Using hardware, a localization circuit may be constructed usinganalog means or digital means in accordance with the invention. Forexample, analog means may comprise an analog comparator for detectingelectrostatic field having a magnitude exceeding a certain predeterminedvalue. If the magnitude of electrostatic field exceeds the predeterminedvalue, the signal from an ESD sensor is reported as a valid ESD signal.Otherwise, the ESD sensor signal is blocked.

[0049] Digital means may comprise an analog to digital converter (ADC)for converting ESD sensor and electrostatic field sensor outputs, and acomparator for detecting electrostatic field having a magnitudeexceeding the predetermined value. The outputs of the ADC and thecomparator may then be fed into a logic AND gate so that if themagnitude of electrostatic field exceeds the predetermined value, avalid ESD signal is genearated. Otherwise, the ESD event is notreported.

[0050] ESD events may also be localized based on changing electrostaticfield. In this case, analog means may comprise a high-pass filter todetect changes in electrostatic field. If the rate of change inelectrostatic field exceeds a predetermined value, the signal from anESD sensor is reported. Otherwise, the ESD sensor signal is blocked.Digital means may comprise an analog to digital converter (ADC) forconverting ESD sensor and electrostatic field sensor outputs and adigital circuit to implement the high-pass filtering function. Theoutputs of the high pass filter and the ESD sensor may be fed into alogic AND gate so that if the rate of change in electrostatic fieldexceeds the predetermined value, the ESD event detection is reported.Otherwise, the ESD event is not reported. It will be appreciated by oneskilled in the art that many variations are possible to implement theanalog and digital means for localizing ESD events. For example, thehigh pass filter function may be implemented using software or firmwarecodes executable by a microprocessor.

[0051] The foregoing description, for purposes of explanation, usedspecific nomenclature to provide a thorough understanding of theinvention. In some instances, well known circuits and devices are shownin block diagram form in order to avoid unnecessary distraction from theunderlying invention. The foregoing descriptions of preferredembodiments of the invention are presented for purposes of illustrationand description, and they are not intended to be exhaustive or to limitthe invention to the precise forms disclosed. It will be appreciated bythose skilled in he art that changes in this embodiment may be madewithout departing from the principles and spirit of the invention, thescope of which is defined by the appended claims.

1. A device for in-situ measurement and recording of at least oneparameter in a process, said device comprising: a sensor for detectingsaid parameter and converting to a sensor output; and a data loggercoupled to said sensor for receiving and logging said sensor output. 2.The device of claim 1 wherein said data logger comprises a timestampingmodule for recording a timestamp with said sensor output.
 3. The deviceof claim 2 further comprising a communication module for communicatingsaid sensor output.
 4. The device of claim 3 wherein said communicationmodule comprises a transmitter and a receiver.
 5. The device of claim 3wherein said communication module comprises an RF (radio frequency)communication module.
 6. The device of claim 1 further comprising adisplay device.
 7. The device of claim 1 wherein said sensor isconfigured to detect a presence of electrostatic field.
 8. The device ofclaim 7 wherein said sensor is configured to measure a magnitude of saidelectrostatic field.
 9. The device of claim 8 wherein said sensor isconfigured to detect a change in said electrostatic field.
 10. Thedevice of claim 1 wherein said sensor is configured to detect anelectrostatic discharge.
 11. The device of claim 10 wherein said sensoris configured to measure a magnitude of said electrostatic discharge.12. The device of claim 1 wherein said data logger comprises an analogto digital converter (ADC) to convert said sensor output into digitaldata.
 13. The device of claim 12 further comprising signal processingcircuitry coupled to said sensor for processing said sensor output. 14.A device for in-situ measurement and recording of at least one parameterin a process, said device comprising: means for detecting said parameterand converting to a sensor output; and means for receiving and loggingsaid sensor output.
 15. The device of claim 14 wherein said means forreceiving and logging comprises a timestamping module for recording atimestamp with said sensor output.
 16. The device of claim 13 furthercomprising means for communicating said sensor output.
 17. The device ofclaim 16 wherein said means for communicating comprises a transmitterand a receiver.
 18. The device of claim 16 wherein said means forcommunicating comprises an RF (radio frequency) communication module.19. A method for in-situ measurement and recording of at least oneparameter in a semiconductor fabrication process comprising a pluralityof stages, said method comprising: (a) monitoring said parameter in astage of said plurality of stages; (b) converting said parameter intodata; (c) logging said data and an identification of said stage; and (d)repeating (a)-(d) for said plurality of stages.
 20. The method of claim19 further comprising timestamping said data.
 21. The method of claim 20further comprising signal processing said data.
 22. The method of claim21 further comprising converting said data into digital data.
 23. Themethod of claim 22 further comprising communicating said digital dataand said identification of said stage to a base equipment.
 24. Themethod of claim 23 wherein said parameter comprises electrostatic field.25. The method of claim 24 wherein said parameter comprises a change insaid electrostatic field.
 26. The method of claim 25 wherein saidparameter comprises an electrostatic discharge.
 27. The method of claim26 further comprising eliminating extraneous electrostatic dischargesbased on said electrostatic discharge and said electrostatic field. 28.A device for in-situ monitoring of at least one environmental parameterin a photolithographic process comprising a plurality of stages, saiddevice comprising: at least one sensor for converting said environmentalparameter of an associated stage into a sensor output; an analog todigital converter for converting said sensor output to digital data; anda communication module to communicate said digital data and anidentification of said associated stage of said plurality of stages. 29.The device of claim 28 further comprising a data logger for logging saiddigital data and said identification of said associated stage.
 30. Thedevice of claim 29 wherein said communication module comprises atransmitter and a receiver.
 31. The device of claim 29 wherein saidcommunication module comprises an RF (radio frequency) communicationmodule.
 32. The device of claim 28 further comprising a display device.33. The device of claim 28 further comprising a sensor for detecting apresence of electrostatic field.
 34. The device of claim 33 wherein saidsensor is configured to measure a magnitude of said electrostatic field.35. The device of claim 34 wherein said sensor is configured to detect achange in said electrostatic field.
 36. The device of claim 28 furthercomprising a sensor for detecting an electrostatic discharge.
 37. Thedevice of claim 36 wherein said sensor is configured to measure amagnitude of said electrostatic discharge.
 38. The device of claim 28further comprising signal processing circuitry coupled to said pluralityof sensors for processing said sensor output.
 39. A device for use inconjunction with a reticle for in-situ monitoring of at least oneelectrical parameter in a semiconductor fabrication process comprising aplurality of stages, said device comprising: a sensor for convertingsaid electrical parameter of a stage into a sensor output; an analog todigital converter for converting said sensor output to digital data; adata logger comprising a timestamping module for logging said digitaldata and an identification of said stage; and an RF (radio frequency)communication module coupled to said data logger.
 40. The device ofclaim 39 wherein said electrical parameter comprises electrostaticfield.
 41. The device of claim 39 wherein electrical parameter comprisesan electrostatic discharge.
 42. A method for in-situ measurement andrecording of at least one parameter in a semiconductor fabricationprocess comprising at least one stage, said method comprising: (a)monitoring said parameter in said stage; (b) converting said parameterinto data; and (c) logging said data and an identification of saidstage.
 43. The method of claim 42 further comprising timestamping saiddata.
 44. The method of claim 43 further comprising: signal processingsaid data.
 45. The method of claim 44 further comprising: convertingsaid data into digital data.
 46. The method of claim 44 furthercomprising: communicating said digital data and said identification ofsaid stage to a base equipment.
 47. The method of claim 46 wherein saidparameter comprises electrostatic field.
 48. The method of claim 46wherein said parameter comprises an electrostatic discharge.
 49. Adevice for monitoring environmental parameters comprising: anelectrostatic sensor for detecting electrostatic field and convertingsaid electrostatic field into a first output; an electrostatic discharge(ESD) sensor for detecting an electrostatic discharge and convertingsaid electrostatic discharge into a second sensor output; an analog todigital converter coupled to said electrostatic sensor and said ESDsensor for converting said first and second sensor outputs to first andsecond digital data, respectively; and a data logger comprising atimestamping module for logging said first and second digital data. 50.The device of claim 49 further comprising an RF (radio frequency)communication module coupled to said data logger.
 51. A method forlocalizing electrostatic discharges (ESD) by detecting electrostaticdischarges and electrostatic field, the method comprising: detecting anelectrostatic discharge and converting it into a first output; detectingsaid electrostatic field and converting it into a second output; anddetermining a valid local electrostatic discharge based on said firstand second outputs.
 52. The method of claim 51 wherein said determiningcomprises determining said valid local electrostatic discharge when saidelectrostatic discharge is combined with said electrostatic field havinga magnitude that exceeds a predetermined value.
 53. The method of claim52 further comprising converting said first and second outputs to firstand second digital data, respectively.
 54. A device for localizingelectrostatic discharges affecting a unit by detecting an electrostaticdischarge and electrostatic field, the device comprising: anelectrostatic sensor for detecting said electrostatic field affectingsaid unit and generating a first output; and an ESD sensor for detectingsaid electrostatic discharge affecting said unit and generating a secondoutput.
 55. The device of claim 54 further comprising: an analogcomparator coupled to said first output for generating a comparatoroutput when said electrostatic field has a magnitude exceeding apredetermined value.
 56. The device of claim 55 further comprising: acircuit coupled to said analog comparator and to said ESD sensor forreceiving said comparator output and said second output, said circuitconfigured to generate a valid ESD signal when said comparator outputand said second output are detected.
 57. The device of claim 54 furthercomprising: an analog to digital converter (ADC) coupled to saidelectrostatic sensor and said ESD sensor for converting said first andsecond outputs to first and second digital data, respectively.
 58. Thedevice of claim 57 further comprising: a digital comparator coupled tosaid first data and generating a comparator output when saidelectrostatic field has a magnitude exceeding a predetermined value. 59.The device of claim 58 further comprising: a circuit coupled to saiddigital comparator and to said ADC for receiving said comparator outputand said second data, said circuit configured to generate a valid ESDsignal when said comparator output and said second data are detected.60. The device of claim 59 wherein said circuit is an AND gate.
 61. Thedevice of claim 60 further comprising: a data logger comprising atimestamping module for logging said first and second digital data. 62.The device of claim 61 further comprising an RF (radio frequency)communication module coupled to said data logger.
 63. A method forlocalizing electrostatic discharges (ESD) by detecting electrostaticdischarges and electrostatic field, the method comprising: detecting anelectrostatic discharge and converting it into a first output; detectinga change in said electrostatic field and converting it into a secondoutput; and determining a valid local electrostatic discharge based onsaid first and second outputs.
 64. The method of claim 63 wherein saiddetermining comprises determining said valid local electrostaticdischarge when said electrostatic discharge is combined with saidelectrostatic field changing at a rate that exceeds a predeterminedvalue.
 65. The method of claim 64 further comprising converting saidfirst and second outputs to first and second digital data, respectively.66. A device for localizing electrostatic discharges affecting a unit bydetecting an electrostatic discharge and electrostatic field; anelectrostatic sensor for detecting a change in said electrostatic fieldand generating a first output; and an ESD sensor for detecting saidelectrostatic discharge and generating a second output.
 67. The deviceof claim 66 further comprising: a high pass filter coupled to said firstoutput for generating a high pass filter output when said electrostaticfield changes at a rate exceeding a predetermined value.
 68. The deviceof claim 67 further comprising: a circuit coupled to said high passfilter and to said ESD sensor for receiving said high pass filter outputand said second output, said circuit configured to generate a valid ESDsignal when said high pass filter output and said second output aredetected.
 69. The device of claim 68 further comprising: an analog todigital converter (ADC) coupled to said electrostatic sensor and saidESD sensor for converting said first and second outputs to first andsecond digital data, respectively.
 70. The device of claim 69 furthercomprising: a high pass filter coupled to said first data for generatinga high pass filter output when said electrostatic field changes at arate exceeding a predetermined value.
 71. The device of claim 70 whereinsaid high pass filter comprises software codes executable by amicroprocessor.
 72. The device of claim 70 further comprising: a circuitcoupled to said high pass filter and to said ADC for receiving said highpass filter output and said second data, said circuit configured togenerate a valid ESD signal when said high pass filter output and saidsecond data are detected.
 73. The device of claim 72 wherein saidcircuit is an AND gate.
 74. The device of claim 73 further comprising: adata logger comprising a timestamping module for logging said first andsecond digital data.
 75. The device of claim 74 further comprising an RF(radio frequency) communication module coupled to said data logger.